For almost 20 years now, I have kept a dream journal. Somewhat sporadically, and I lost it all about halfway through, but I guess I can rightfully claim to have more of an overview of my dreams than most people I know.
For much of that time, I tried to decipher them, to find some kind of meaning, symbolism or the like, inside them. I even kept lists of "symbols" to be able to do a little bit of statistics on them.
Ultimately, what I came up with was precious little. Nothing, really, that I wouldn't have come up simply by looking over my journal once in a while.
For quite a few years, I kept dreaming about elevators that failed in all kinds of dangerous ways. I also dreamed a lot about public transport crafts. Invariably, those drove around the whole town in all the wrong directions, and I never reached my goal. This was a time when I was rather insecure and pretty depressed, so it made sense.
I dreamed a few times about an ex girlfriend, where the breakup had been rather dramatic. Understandable.
And a few years later, at a new job that made me the most money I had ever earned, I dreamed about very big and respectable houses, such as museums and the like.
When I was out of a job or concerned about my professional future, I tended to dream about my very first profession (as a bookseller).
I had the usual dreams about flying, which were fun, and very few, but rather intense, nightmares.
A few times, I dreamed about uncanny twins, and it seemed to coincide with upcoming big decisions.
People from my past and present show up in my dreams, of course, and there seem to be certain (very odd) rules. For example, I never dream about my current girlfriend, I often find myself with an anonymous "group of friends", etc.
And that's about it. It's not an awful lot, certainly no prophecies or clairvoyance. No out-of-body experience or astral projection. In all those years, despite some efforts, I had exactly one lucid dream, and one that was somewhat semi-lucid. I was never able to find any "special" meaning. My dreams never told me anything I didn't already know. They never offer any guidance or insight or spiritual experience.
So, my conclusion is that there is nothing to dream symbols, and there is nothing supernatural going on in dreams. Dreams can be fun, they're certainly interesting, but they have no meaning.
Most probably, they are just a way for the brain to reorganize its internals.
It's a bit sad, perhaps, but that's how it is.